John Piper said that rocks are not simply grey in fact they are not grey at all. However at first impression as seen in this photograph of rocks near The Darren in Dare Valley Country Park, they do look very grey. All the rocks here are not really the colour of rocks at all as they are totally covered in lichens. We are looking at the colour of lichens.
Where the rock has been newly recently exposed then we can see something of its true colour, in this case reddish brown and dark blue. There are hardly any rocks up here that actually look like this. These fresh rocks are also sharp edged and angular whereas the ones in the top photo have been weathered into rounded corners and deep cracks almost like the hide of an animal such as an elephant.
These are what are generically known as map lichens because they form patches of colour like the countries represented on an atlas of the world. I have shown these here because they are an unusual colour in this area and they stand out from some considerable distance.
The more typical lichen is this grey one, with other patches of pale (almost white) and yellow map lichens. In the top left is a patch of a thicker foliose lichen with a range of different greys. Other lichens in this area can be a deep brown in hue.
So when it comes to painting a rock where do you start? In effect it can be almost any colour if you look closely enough because the patches of different coloured lichen can occur anywhere in any combination. Here I have kept the dark brown lichens where they occurred naturally and the intense sienna in the background represents the dead bits of rush. And the blue, well that's there if you look hard enough!
